When scientists talk about the cryosphere, they mean the places on Earth where water is in its solid form, frozen into ice or snow. Read more ...

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Tag Archives: minimum

The U.S. Coast Guard Cutter Healy encountered only small patches of sea ice in the Chukchi Sea when this photograph was taken on July 20, 2011. (Courtesy NASA Goddard Space Flight Center)

Guest post by Walt Meier, NSIDC Scientist

Arctic sea ice set a record minimum extent in September 2012, far below the previous record low in 2007. Summer extents have been far lower than average for the last decade, with several record or near-record years. Looking at the numbers, one is tempted to think that the Arctic Ocean may reach nearly sea ice-free conditions within just a few years. But most expert analyses indicate that we’re likely at least a couple decades away from seeing a blue Arctic Ocean during the summer.

This graph shows the yearly trend toward later Arctic sea ice minimum dates, but also illustrates the wide variability from year to year. Credit: NSIDC

A reader recently asked if the date of the annual Arctic sea ice minimum is shifting later each year. And if so, is that shift a sign of heat being stored in the Arctic region?

According to the satellite record, Arctic sea ice generally melts to its minimum annual extent between the first and third week of September, after which ice begins freezing again. In recent decades, the Arctic has been gaining heat: Air, land, and ocean temperatures in the region have been slowly rising, and scientists have noted dramatic reductions in summer sea ice extent, as this heat causes more ice to melt away. But is this heat causing sea ice to form later each fall? Continue reading →

Figure 1. This graph shows Arctic sea ice extent for spring and summer months. Light blue indicates the ice extent this year, dark blue shows ice in 2010, and green indicates ice extent during 2007, which was the record low year for Arctic sea ice. The gray line shows the 1979 to 2000 average ice extent, while the gray area around the gray line shows the standard deviation range for the data, which represents the range of normal variability. Credit: NSIDC

So far this summer, Arctic sea ice has been melting at a record pace. Satellite data, which go back to 1979, show that ice extent is currently lower than it was at the same time in 2007, the year that went on to shatter all previous records for low ice extent in September, the end of the melt season (Figure 1). It is not yet clear if the ice will hit a new record low this September. But whether or not the ice extent sets another record, Arctic sea ice is continuing its long-term decline, a trend that researchers say is related to warming temperatures in the Arctic.

Last week, an international group of researchers released their best estimates for Arctic sea ice extent over the summer melt season. The scientists are compiling their estimates so that they can better predict changes in Arctic sea ice. Credit: SEARCH Sea Ice Outlook

Average Arctic sea ice extent this May was the third lowest in the satellite record. Does that mean that ice extent will reach a new record low this summer? Or will it recover somewhat over recent years?

Last week sea ice scientists from around the world shared their best answers to those questions, in the June report of the Sea Ice Outlook. For the report, the researchers used a variety of methods to predict how sea ice will behave this summer, such as statistical methods or computer models. Continue reading →